Feminine hygiene devices such as sanitary napkins and pantiliners are designed to collect, absorb, and retain bodily discharges. Feminine hygiene devices typically comprise a liquid pervious topsheet, an absorbent core, and a liquid impervious backsheet. Feminine hygiene devices are typically attached to the wearer's panty with a pressure sensitive adhesive to keep the feminine hygiene device under the wearer's vaginal opening and near the wearer's body to intercept discharge.
Approaches for achieving proper fit include using shaped absorbent cores and shaped inserts to shape the feminine hygiene device. Feminine hygiene devices having these features may not be able to be folded flat. Packaging feminine hygiene devices that cannot be folded flat can be inconvenient and uneconomical. Furthermore, shaped elements may not be sufficiently pliable to conform to a wide range of motions and may feel bulky to wearers of the feminine hygiene device.
To perform optimally, feminine hygiene devices should conform to the shape of the woman's pudendal region. Presently, some designers believe that the coronal profile of a feminine hygiene device should have the shape of an inverted “V” in the rear to fit between the woman's buttocks and have a “W” shape in the middle to fit around her labia. Some designers also believe that a feminine hygiene device should be slightly cup-shaped in the woman's pubic area. Some designers believe that these shapes should not merely project from a flat feminine hygiene device but should be contours along a feminine hygiene device that is curved from front to rear to fit with the curvature of the wearer's pudendal region as viewed from a sagittal perspective. For feminine hygiene devices having a “W” shaped middle area and an inverted “V” shaped rear area, there can be a ridge along a portion of the length of the feminine hygiene device defined by the middle vertex of the “W” and the vertex of the inverted “V.”
For the ridge to bend to conform to the curvature of the wearer's pudendal region as viewed from a sagittal perspective, the ridge must be shortened. Conventional materials and structures for absorbent cores may be unable to shorten, in a controlled manner, along the ridge as the absorbent core is bent. Rather, as the ridge is shortened by bending, the absorbent core material buckles, crumples, and wrinkles in an uncontrolled manner. An absorbent core that is buckled, crumpled, and wrinkled in an uncontrolled manner along the ridge is unlikely to conform to the wearer's body satisfactorily. For wetted absorbent cores, buckling, crumpling, and wrinkling can be even more pronounced due to the loss of mechanical integrity caused by wetting.
A simple physical model illustrative of the problem facing designers of feminine hygiene devices having a “W” shaped middle area, an inverted “V” shaped rear area, and a ridge along a portion of the length of the feminine hygiene device can be created using a rectangular sheet of writing paper. The writing paper is folded in half such that the fold line has the same length as and is aligned with the longer dimension of the writing paper. Next the fold is opened slightly. This creates a “beam” having an inverted “V” cross section. When the beam is bent along the length of the beam, such that the fold line is on the side of the beam being shortened by compressive stresses, the fold line buckles, crumples, and wrinkles uncontrollably.
One approach for allowing the ridge of the feminine hygiene device to be shortened without uncontrollably deforming the absorbent core is to remove absorbent material from the absorbent core in areas where shortening occurs. As the core is bent, the openings created by removing absorbent material can close, thereby allowing controlled shortening of and along the ridge. Openings in the absorbent core can adversely interrupt fluid transport in the absorbent core, can be challenging to manufacture, and can reduce the structural integrity of the absorbent core.
Accordingly, there is a need for feminine hygiene devices that can conform to the shape of a woman's pudendal region as she moves through her day. There is also a need for feminine hygiene devices that can conform to the shape of a woman's pudendal region and be folded flat for packaging and storage. A further need is for feminine hygiene devices having an absorbent core that performs effectively when portions of the absorbent core are shortened.